Tatemichi, M., Sasazuki, S., Inoue, M. & Tsugane, S. Different etiological role of Helicobacter pylori (Hp) infection in carcinogenesis between differentiated and undifferentiated gastric cancers: a nested case-control study using IgG titer against Hp surface antigen. Acta. Oncol. 47, 360-365